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In a season dominated by an unprecedented drought, soybean grain yield and leaf sulfur levels were not significantly affected by two starter fertilizers containing supplemental sulfur.

Recent research publications have highlighted potential
sulfur (S) deficiencies in corn and soybeans in the North Central region. Sulfur
is not mobile within the plant, so symptoms usually appear in the new growth. Atmospheric
deposition used to supply a considerable amount of plant available S (about 8
to 15 lbs./A annually), but with the implementation of the Clean Air Act, this amount has
significantly decreased. Another important source of S is the soil organic
matter. When organic matter decomposes, S is released as a sulfate ion into the
soil solution. In Michigan, sulfur deficiencies are most likely to occur on
coarse-textured soils with low organic matter. Other factors that may contribute
to the need for supplemental S include increased crop removal rates in intensive
cropping systems and lack of S impurities in major fertilizer sources.

In 2012, an on-farm research project was
conducted in Perry, Mich., where two liquid starter fertilizer products, eNhance® and Access® containing S, were applied at the rate of 2 quarts/A in
2X2 band and compared with untreated (Table 1). The treatment strips were
randomized and replicated four times. In addition to S, these two products also
contained some micronutrients. The soil characteristics were pH = 6.3, Cation
Exchange Capacity (CEC) = 5.1 meq/100g and soil organic matter = 1.7 percent.

Although statistically significant, the yield differences
between the three treatments were less than two bushels. Access®, which has the
highest S content, produced the highest soybean yield, but eNhance® produced no
yield response. The S sufficiency range for soybeans is
between 0.20 to 0.50 percent. All three treatments in our study were within
this range. Drought conditions in 2012 may have contributed to reduced nutrient
uptake in 2012. Despite this field being a mineral soil
with low CEC and low organic matter, the expected increases in soybean yield and
sulfur uptake from supplemental S were not evident. However, this data
represents only one site and one year.

This study was funded by the Michigan Soybean Promotion Committee. The author wishes
to thank Mike Staton, senior MSU Extension educator; Will Willson, soybean
producer from Perry, Mich.; and Brian Martindale, Agro-culture liquid fertilizer
dealer from St. Johns, Mich., for their collaboration in this study.